A pyrrole compound having a substituted sulfonyl group at the 1-position (hereinafter to be referred to as a sulfonylpyrrole compound) may be useful as an acid secretion inhibitor (proton pump inhibitor), a therapeutic drug for a neoplastic disease or an autoimmune disease.
A 3-cyanopyrrole compound is used as an intermediate for producing a sulfonylpyrrole compound. Patent document 1 describes the following method as a production method of a 3-cyanopyrrole compound.
wherein r1 is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, r7 is a cyano group or a substituted carboxyl group, and r8 is a hydrogen atom, an optionally substituted hydrocarbon group, an optionally substituted heterocyclic group, a chlorine atom or a fluorine atom.
Patent document 1 discloses that the reduction reaction used to obtain compound (XIII) from compound (XII) can be performed by catalytic hydrogenation in the presence of a hydrogen source and a metal catalyst.
However, this method is not industrially advantageous since it requires a filtration operation to remove metal catalyst after the reaction and the operation is complicated.